The present invention is directed to devices and methods for reversing the polarity of fiber optic cable connections. In particular aspects, the invention is directed to adapters for receiving and interconnecting cables having optical fibers therein.
In the fiber optic communication field, cables are used that contain a pair of, or sometimes more, individual optical fibers. Connectors, two of which that are being used today include the SC-DC and the MT-RJ connectors, are placed on the ends of the cables to retain the fibers in a particular orientation and position with respect to one another. The connectors include ferrules to hold and align the optical fibers. The fibers are generally secured within the ferrule using epoxy and then polished to ensure clear signal transmission.
When two optical cables must be joined at an interface, such as a wall or a connector panel, adapters are used to provide receptacles within which the connectors reside. Conventional adapters are similar in many respects to the well-known wall-mounted telephone jack that receives the connector on the end of a telephone cord and allows the wires inside the telephone cord to be interconnected with other circuits associated with the adapter. Like the connector for a telephone jack, fiber optic connector housings usually incorporate a keying arrangement that ensures that the connector can be inserted into the adapter only in a predetermined orientation with respect to the adapter.
Unlike telephone jacks, however, fiber optic adapters are formed to receive two connectors from opposite ends. These two ends are sometimes referred to as the user end and contractor end. The adapter locates the two connectors in an end-to-end relation such that the fibers within the two connectors are aligned and light can be transmitted from the optical fibers within one of the connectors to the optical fibers in the other connector.
Currently, fiber optic cables most often contain two optical fibersxe2x80x94a transmitting fiber and a receiving fiber. When the two connectors are inserted into the adapter, the transmitting fiber of one connector is aligned with the receiving fiber of the other connector, and vice versa. Occasionally, these two fibers become inadvertently reversed when the connector is installed onto the end of the cable. If this occurs, the polarity of the connection will be reversed, and the fiber optic system will not work properly when the connectors are installed in the adapter. Until now, the only method for resolving such a problem has been for an installer to cut the connector off the end of the cable and install a new connector so that the fibers are properly arranged. Because of the requirement to use epoxy to secure the fibers, and polish the fiber ends, the procedure is difficult to accomplish in the field. Even when performed under the best circumstances, however, there are risks of errors in the installation of the connector or damage to the fiber optic elements. In addition, installers need to carry additional connectors along with them and, if those are forgotten, lost, or used up, correction of the problem can be extremely difficult.
The present invention provides devices and methods that permit simple correction of a fiber optic polarity reversal problem. In particular embodiments, adapters are described having receptacles to receive a connector on a first end, or user end, and on a second end, or contractor end. Both the receptacles provide keying arrangements so that the connectors can be received only when correctly oriented with respect to the adapter. The keying arrangement on the contractor end, however, is reversible so that the connector may be inserted in one of two predetermined orientations, at the behest of the contractor or installer.
In some preferred embodiments described herein, an adapter provides a non-standard receptacle on the contractor end having a main entrance that permits entry and residence of the housing for a connector, and a pair of key ways. One of the key ways is located on the upper side of the main entrance, while the other key way is located on the lower side. A key excluder is selectively disposable within either one of the key ways to prevent the key portion of a connector from being disposed within that key way.
The adapter is preferably provided to a contractor and used in a xe2x80x9cdefaultxe2x80x9d configuration in which the key excluder is placed in a predetermined one of the two key ways. This default configuration allows a connector to be received by the adapter on the contractor side in an orientation intended to correspond to a connector inserted into the user end so that polarity between the connectors is correct. In the event of a reverse polarity mistake, the installer removes the key excluder and inserts it in the other key way. This allows the connector on the contractor side to be inverted when reinserted to the adapter receptacle. A number of different configurations for key excluders are described.
In alternative embodiment, adapters are described that only permit connectors to be inserted in a reverse configuration. This adapter can be substituted for a standard adapter when a polarity reversal problem is detected.
Embodiments are described for correction of a polarity reversal problem to be corrected where either MT-RJ or SC-DC connectors are used.
In a further embodiment, an exemplary jumper is described that can be interposed between a connector and adapter to reverse the polarity of the fibers associated with the connector.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as claimed.